Variable torque brake for a winding reel



Jan. 14, 1964 P. TROMBETTA 3,117,742

VARIABLE TORQUE BRAKE FOR A WINDING REEL Filed Sept. 13, 1961 2 Sheets-Sheet 1 FIG I .2

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IN VEN TOR. PANFILO TROMBETTA By WM ATTORN YS Jan. 14, 1964 P. TROMBETTA 3,117,742

VARIABLE TORQUE BRAKE FOR A WINDING REEL Filed Se pt. 13, 1961 2 Sheets-Sheet 2 INVEN TOR. PANFILO TROMBETT By 2/ 41! (gum ATTORNEIS United States Patent 3,117,742 VARIABLE TORQUE BRAKE FOR A WINDING REEL Panfilo Trombetta, 329 N. Milwaukee St., Milwaukee 2, Wis. Filed Sept. 13, 1961, Ser. No. 137,764 3 Claims. (Cl. 242156.2)

This invention relates to a brake, and more particularly, to a variable torque brake useful, for example, in connection with the winding or unwinding of materials on reels.

When winding materials, such as rope, wire, steel strips and the like, onto a reel, the winding radius of the reel is constantly changing in relation to the amount of material wound on the reel. In order to control the speed of such a reel, which is either being wound or unwound, it is required that a brake applied for stopping such a reel should have a torque which varies according to some appropriate function of the amount of material wound on the reel at the time that it has to be stopped. It will be appreciated that if the force or pull on the material to be wound remains constant, then the torque which must be overcome to stop the reel will be proportional to the winding radius, which varies with the amount of material wound on the reel. Moreover, reels containing variable amounts of material have a variable moment of inertia which must be overcome and a greater amount of stored kinetic energy to be consumed in order to stop the reel; the inertia of the wheel and material being greater when the reel contains a large amount of wound material.

In cases where material is being unwound from one reel and wound onto another reel, two brakes are required, one for the unwinding reel and one for the winding reel. In order to prevent the material from piling up between reels, the two brakes must be capable of being instantaneously and continuously adjusted to maintain proper relations of torque between the two brakes in order to maintain some tension on the material at all times. According to a different requirement of brakes in winding and unwinding machines, in the process of rewinding material, which is already wound on a reel, in order to maintain a constant tension on the material a brake is required upon the reel that is being unwound. In this case the torque must be applied at all times and must vary as a function of the diameter of the wound reel.

It is therefore an object of the present invention to provide an improved variable torque brake.

A further object of the present invention is to provide a brake for controlling a winding reel and which has a torque proportional to the amount of material wound on the reel at the time that it has to be stopped.

Another object of the present invention is to provide a brake capable of producing a variable automatically adjustable torque to maintain either a constant or variable ratio between its own torque and the torque of at least one additional brake to maintain, in turn, a constant or relatively constant tension on the material between a winding reel and an unwinding reel.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and [forming a part of this specification.

Briefly stated, the present invention relates to a brake or control adapted to control a rotatable shaft which carries a reel for having material wound thereon and unwound therefrom. The winding diameter of the reel will, of course, vary generally in response to the amount of material wound thereon. Brake means, such as a friction brake, are operatively connected to control the shaft. According to the present invention, means are associated with the reel for sensing the winding diameter of the reel and additional means operatively interconnect the sensing means and the brake for varying the torque of the brake in response to the winding diameter of the reel.

In one preferred embodiment of the invention, the friction brake is electromagnetically applied by a solenoid and a sensing device is provided which rides on the surface of the material on the reel, thereby sensing the Winding diameter of the reel. The sensing device controls a rheostat which is in an electric circuit with the solenoid and which is effective to alter the current flow through the solenoid in response to the winding diameter of the reel, thereby to vary the torque of the brake.

In another embodiment, the brake is spring-set and a weight is provided as the sensing device which rides on the material on the reel. A portion of the setting force is counter-balanced by the weight in response to the winding diameter of the reel.

The nature of the invention will best be understood when described in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of a variable torque brake according to the present invention;

FIG. 2 is an elevational view of the brake of FIG. 1 with certain portions broken away;

FIG. 3 is an elevational view illustrating a modified rheostat arrangement which may be used with the brake of FIGS. 1 and 2;

FIG. 4 is a plan view of a variable torque brake according to another embodiment of the present invention; and

FIG. 5 is an elevational view of the brake of FIG. 4 with certain parts thereof broken away.

Referring now to the drawings, and particularly to FIGS. 1 and 2 thereof, there is illustrated an improved variable torque brake according to the present invention and connected to control a winding reel or drum 10. The winding reel 10 is keyed or otherwise secured to a shaft 12 which may be driven by an electric motor (not shown) or otherwise to turn the winding reel 19 to wind a windable material, here shown as a wire rope 14-, upon the winding reel 10. The winding reel 10 includes a hub 10a interconnected by a pair of spaced sides 1% so that the wire rope 14 as it is wound upon the hub 10a of the winding reel 10 may, in the illustrated embodiment, form a plurality of side-by-side strands; but additionally will form a plurality of layers of side-by-side strands so as to fill the hub 10a between varying diameters d and d (FIG. 2) as the wire rope 14 is wound upon the reel 10, as illustrated in phantom in FIG. 2.

In order to control the shaft 12 and to stop a winding or unwinding operation of the reel 10, a friction brake assembly 16 is operatively associated with the shaft 12. Specifically, the friction brake assembly 16 includes a brake drum 18 secured to the shaft 12 by a key 20 or otherwise, and a complementary brake shoe 22 frictionally engageable with the brake drum 1S and containing a friction material 24 on its inner surface.

In order to apply the friction brake assembly 16 to control the shaft 12, there is provided an electromagnetic solenoid generally illustrated at 26. Although the electromagnetic solenoid 26 may be of a known design, briefly, it includes a stationary frame portion 28 carrying an electromagnetic coil or winding 30 and additionally includes a plunger 32 axially slidable through a central opening 34 in the solenoid 26 in response to the energization of the Winding 30. The plunger 32 is pivotally connected to one end of a brake arm 36 and the other end of the brake arm 36 is pivotally mounted to a pivot pin 38. Moreover, the brake shoe 22 is pivotally mounted to the brake arm 36 by a pivot pin 4(9- intermediate the ends of the brake arm 36. It will be appreciated that energization of the winding 30 is elfective to draw the plunger 32 upwardly, as viewed in FIG. 2, thereby applying the brake assembly 16 to stop the shaft 12. The brake is therein illustrated in the applied position and it is noted that the gap formed between the upper end of the plunger 32 and a pole 28a is not closed, but that all the force of the solenoid 26 is transmitted directly to the brake arm 36 and the reaction is applied directly to the brake drum 1% by the brake shoe 22. As is well known, the force produced by the solenoid 26 is a function of the current flowing through the winding 30.

According to the present invention, means are provided for controlling the current fiow through the solenoid 26 in relation to the winding diameter of the reel 10. Specifically, such means includes a sensing device for gauging the winding diameter of the reel and including a sensing arm 42 pivotally mounted intermediate its end about a pivot pin 44. One end 42a of the sensing arm carries a pad 46 which during a braking operation rides on the surface of the material on the reel 10. The other end 42b of the arm 42 carries an electrical contact 48 electrically isolated from the arm 42 and forming a sliding contact of a variable rheostat 50. The rheostat 50 is provided with a winding 52 and the contact 48 is adapted to make sliding contact with the turns of the Winding 52 as the arm 42 is moved in response to the changes in the winding diameter of the reel 10.

In order to vary the current flow in the solenoid 26, the winding 52 of the rheostat 59 is serially connected with the winding 30 of the solenoid 26 and the circuit is provided with a pair of terminal means 54 and 56 adapted to be connected to an external power source (not shown). Specifically, the contact 48 is electrically connected to one end of the winding 30 by a lead 58; the other end of the winding 30 is connected to the terminal means 54 by the lead 64); moreover, one end of the winding 52 is connected to the terminal means 56 by the lead 62.

From the above detailed description, the operation of the improved variable torque brake is believed clear; however, brieflly, it will be appreciated that during the process of winding and unwinding, the Winding diameter of the reel 10 varies betweenthe minimum radius, identied as d in FIG. 2 to the maximum radius identified as d as the reel 10 approaches a full reel of material. Moreover, it will be appreciated that if a continuous pull is applied to the wire rope 14, the torque necessary to stop the shaft 12 will be a function of the amount of material wound on the reel 10. Furthermore, during the process of unwind-ing the sensing arm 42 is movable from the position illustrated as A, FIG. 2, in phantom, to the position illustrated in solid therein and identified as B. The position of the sensing arm 42 is effective incrementally to vary the value of impedance or resistance inserted in the circuit by the rheostat 50. Of course, it is understood that the pad 46 may not actually ride on the material being wound except during a braking operation and so long as the reel 10 is rotating without braking, the sensing arm '42 may be held from engagement with the rope 14 through a solenoid or air cylinder or otherwise. When the brake is applied to the reel 10, the sensing arm 42 is released to engage the material on the reel 10, as illustrated in FIGS. 1 and 2, prior or simultaneously with the excitation of the solenoid 26. In this manner the pad or weight rides on the material being wound only between the time that the brake is set and the time that the reel 10 comes to a stop. Of course, it is also understood that when the brake must be continuously applied to the reel It to control the tension of the material, the pad 46 would bear upon the rope 14 on the reel 10 at all times. As the current flow through the solenoid winding 30 depends upon the voltage applied, impedance of the winding 30, and the impedance of the variable rheostat 50 which is inserted in the circuit, the

current flow through the winding 30 will be nearly proportioual to the winding radius d to d of the reel 10 and the stopping torque applied by the friction brake assembly 16 will therefore be a function of the winding diameter of the reel.

The improved variable torque brake illustrated in FIGS. 1 and 2 is applicable to either direct current or alternating current applications. However, inv an alternating current apparatus, the power lost in the series resistance of the winding 52 in the rheostat 50 may be eliminated by the substitution of a variable voltage transformer in place of the rheostat 56; the output of the transformer could then be used either in connection with an alternating current apparatus such :as an alternating current solenoid or other motive unit as a Recipromotor or Semotor, or the output may be rectified and used as direct current. The power lost in the rheostat 50 would thereby be eliminated.

The embodiment of FIG. 3 illustrates a modified rheostat arrangement which provides for a greater variation in the resistance of the rheostat with a given movement of the sensing arm. The rheostat arrangement therein illustrated is suitable for use with the variable torque brake illustrated in the embodiments of FIGS. 1 and 2 and, therefore, similar parts of FIGS. 1, 2, and 3 are identified by the same numeral. Referring now to the embodiment of FIG. 3, there is illustrated a variable rheostat provided with a winding 92 and a contact 94 on a pivoted contact arm 96 and positioned to make sliding contact with the turns of the winding 2. A sensing arm 98 is keyed or otherwise secured at one end to a pivotally supported shaft 10% and the other end thereof (not shown) is adapted to ride on the surface of the material on the Winding reel. Movement of the sensing arm 98 rotates a gear 102' keyed or otherwise secured to the shaft 109. Additionally, a pinion gear 104, smaller than the gear 102, is keyed or otherwise secured to a shaft 166 which positions the contact arm 96 and is in operative mesh with the gear 102 to be rotated thereby.

It will be appreciated that pivoting of the sensing arm 93 rotates the gear 102 which, in turn, drives thepinion gear 10'4- to move the contact 94 over the winding 92. Moreover, since the gear 102 is of a larger diameter than the piniongear 184, the pinion gear 104 is driven through a wider "angle than that through which the sensing arm 98 moves and, therefore, a wider range of control is more readily obtained on the rheostat 99.

The rheostat arrangement illustrated in FIG. 3 may be connected in a circuit with a solenoid such as the solenoid illustrated at 26 in FIGS. 1 and 2. Specificially, the contact 94 may be connected to the winding 30 through the lead 58 and the winding 92 may be connected to the terminal means 56 through the lead 62.

Of course, it is understood that the braking force may have any desired load characteristic including a straight line function. Although the gear 162 and the pinion gear 164' are herein illustrated as circular, it is to be understood that the gears may be elliptical in shape, or have other irregular contour to obtain any desired variation of torque according to a predetermined variable function of the diameter of the reel 10. Moreover, the braking torque may readily be varied in relation to the diameter of the material on the reel by the use of a Semotor which [has its stator mounted relative to a disk in such a manner that the stator can be moved radially of the disk in response to the winding diameter of the reel. Thetorque resulting on the shaft of the Semotor will vary as a function of the position of the stator along the radius of the disk. This is based upon the fact that the tangential force exerted by the Semotor stator upon the disk remains constant as long as the voltage and frequency applied to this Semotor is kept constant. Therefore, by moving the Semotor stator radially in and out relative to the winding diameter of the reel it is possible to obtain a variable torque output on the motor shaft. The Semotor stator could, for example, replace the rheostat G in the embodiment of FIGS. 1 and 2, being mounted at'contact 48 thereof to move in and out relative to the diameter of the winding reel 10.

FIGS. 4 and 5 illustrate an improved variable torque brake wherein the brake is mechanically applied by a spring and wherein a portion of the spring bias is counterbalanced in relation to the winding diameter of the reel. Similar parts of the embodiment of FIGS. 4 and 5 and of the preceding embodiments are designated by the same numerals as in the preceding embodiments. Referring now to FIGS. 4 and 5, there is provided the winding reel keyed or otherwise secured to the shaft 12 and adapted to have wound and unwound thereon a suitable windable material, therein illustrated as the wire rope 14. The winding reel 10 includes the hub 113a interconnected by the pair of spaced sides 10b so that the Wire rope 14 as it is wound on the hub 100: forms a plurality of layers of side-by-side strands so as to fill the hub 10a between varying diameters as the Wire rope 14 is wound upon the reel 10. i

In order to control the shaft 12 and to stop a winding or unwinding operation of the reel 1%, a friction brake assembly 116 is operatively associated with the shaft 12. Specifically, the friction brake assembly 116 includes a brake drum 118 keyed or otherwise secured to the shaft 12, and a complementary brake shoe 122 frictionally engageable with the brake drum 118 and containing a friction material 124 on its inner surface engageable with the drum 118.

In order to apply the friction brake assembly 116 to control the shaft 12, there is provided a brake arm 136 pivotally mounted intermediate its length about a fixed pivot pin 13% and pivotally supporting the brake shoe 122 through a pivot pin 140; A tension spring 142 is provided interconnecting one end 136a of the brake arm 1'36 and a stationary portion of the brake assembly 116 to bias the brake arm 136 counterclockwise, as viewed in FIG. 5, about the fixed pivot pin 138. Of course, it is to be understood that means (not shown) may be pro vided for holding the brake shoe 122 out of engagement with the brake drum 118 against the bias of the tension spring 142 when it is desired that the brake assembly 116 be in a released condition.

According to the present invention, means are provided for counterbalancing the brake applying force of the tension spring 142 in relation to the winding diameter of the reel 10. Specifically, such means includes a sensing device for gauging the winding diameter of the reel 16 including a sensing arm i44- pivotally mounted at one end about a fixed pivot pin 146. The other end of the sensing arm 144 is provided with a weight 148 which rides on the surface of the material on the reel 19. A counterbalancing compression spring 156 interconnects an intermediate portion of the sensing arm 144 and an overhanging end 136k of the brake arm 136. It will be appreciated that the force of the spring tends to bias the brake arm 136 clockwise, as viewed in FIG. 5, in the opposite direction from the spring 142, thereby being effective to counterbalance a portion of the force from the spring 142.

From the above detailed description, the operation of the improved variable torque brake is believed clear; however, briefly, it is understood that during the process of winding and unwinding the winding diameter of the reel 1! varies between the fully wound position illustrated in phantom in FIG. 5 and identified as A, to, for example, an intermediate position illustrated in solid therein and identified as B, to a minimum radius wherein the reel 10 is unwound. It will be appreciated that if a continuous pull is applied to the wire rope 14, the torque necessary to stop the shaft 12 will be substantially in proportion to the winding diameter of the reel 1% and therefore to the amount of the material wound on the reel 11 Moreover, during the process of winding and unwinding, the weight 148 on the sensing arm 144 moves over the surface of the rope 14 wound on the reel 10, pivoting the sensing arm 144 about the pivot pin 146. This movement of the sensing arm 144 is effective incrementally to vary the load exerted on the brake arm 136 by the compression spring 15:), thereby to incrementally vary the effective setting load on the brake assembly 116. The weight 148, of course, must be sufiicient to always ride on the surface of the rope 14 so as continuously to apply the force of the spring 1'50 against the brake arm 136. As the counterb-allancing force of the spring 150 is varied in relation to the winding diameter of the reel 10, the stopping torque applied to the shaft 12 by the friction brake assembly 116 will be approximately proportional to the Winding diameter of the reel 10.

While several preferred embodiments have been illustrated, many modifications will occur to those skilled in the art. For example, when winding or unwinding a reel at a constant speed of material, the angular velocity of the reel is inversely proportional to the winding diameter of the wound material; therefore, by mounting a ball speed governor on the reel shaft it is possible to adjust a brake according to the speed of the shaft and, consequently, to apply a braking torque in relation to the winding diameter on the reel. It is therefore intended in the appended claims to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. A variable torque brake operatively connected to a winding reel of the type adapted to hold a variable amount of material at a varying diameter, said brake including a friction brake assembly operatively connected to control said'reel and spring means for setting the brake, means for continuously sensing the winding diameter of the material on the reel, and additional spring means connected between said brake and the said means for sensing the winding diameter for counterbalanoing a portion of the force of the first-mentioned spring means in response to the winding diameter of said reel to vary the torque of said brake in approximate proportion to the winding diameter of said reel.

2. In combination, a rotatable shaft, a reel on said shaft adapted to hold material thereon, the winding diameter of said reel varying in response to the amount of material wound thereon, a brake drum operatively connected to said shaft, a brake shoe operatively positioned to frictionally engage said brake drum, spring means operatively connected with said shoe for biasing said shoe into frictional engagement with said drum, sensing means including a Weight riding on the surface of the material on said reel for sensing the winding diameter of said reel, and means including additional spring means operatively connected between said brake shoe and said sensing means for counterbalancing a portion of the setting force of the first-mentioned spring means and actuated by the said sensing means to vary the bias of said shoe against said drum in response to the size of the winding diameter of said drum.

3. A variable torque brake operatively connected to a winding reel of the type adapted to hold a variable! amount of material at a varying diameter, said brake including a brake drum for controlling the winding reel; a brake arm pivotally mounted about a pivot means intermediate its length; a brake shoe mounted on said brake arm on one side of said pivot means and operatively positioned to fnictionally engage said brake drum, tension spring means operatively connected to said one side of said brake arm for biasing said shoe into frictional engagement with said drum; sensing means for sensing the winding diameter of said reel and including a sensing arm pivotally mounted at one end, and a Weight on the other end of said sensing arm riding on the surface of the material on said reel responsive to the winding diameter of said reel; and compression spring means in- 8' terposed between said arms operatively engaging the 1,630,376 Derry May 31', 1927 other'end of said brake arm and connected intermediate 1,822,495 Laycock Sept. 8, 1931' said sensing arm to counterbalance a portion of the set- 1,925,580 Anderson Sept. 5, 1933' ting force of the first-mentioned spring means for vary- 2,750,921 Purdy June 19, 1956. ing the bias of said shoe against said drumin response 5 FOREIGN PATENTS to the size of the windingdiameter of said drum. 7

842,328 Germany June 26, 1952 References Cited in the file of this patent 7 r at Britain Mar, 19, 1935 UNITED STATES PATENTS 822,601 Great Britain Oct, 28, 1959 1,353,401 James Sept. 21, 1920 10 

1. A VARIABLE TORQUE BRAKE OPERATIVELY CONNECTED TO A WINDING REEL OF THE TYPE ADAPTED TO HOLD A VARIABLE AMOUNT OF MATERIAL AT A VARYING DIAMETER, SAID BRAKE INCLUDING A FRICTION BRAKE ASSEMBLY OPERATIVELY CONNECTED TO CONTROL SAID REEL AND SPRING MEANS FOR SETTING THE BRAKE, MEANS FOR CONTINUOUSLY SENSING THE WINDING DIAMETER OF THE MATERIAL ON THE REEL, AND ADDITIONAL SPRING MEANS CONNECTED BETWEEN SAID BRAKE AND THE SAID MEANS FOR SENSING THE WINDING DIAMETER FOR COUNTERBALANCING A PORTION OF THE FORCE OF THE FIRST-MENTIONED SPRING MEANS IN RESPONSE TO THE WINDING DIAMETER OF SAID REEL TO VARY THE TORQUE OF SAID BRAKE IN APPROXIMATE PROPORTION TO THE WINDING DIAMETER OF SAID REEL. 